The correct answer is option 2: Kidney.

Malaria is a disease caused by the parasite Plasmodium, which is transmitted to humans through the bite of infected mosquitoes. Once inside the human body, the parasite goes through different stages of development and replication.

Option 1: Liver. The liver is the initial site of infection for Plasmodium. After being transmitted through a mosquito bite, the parasite travels to the liver where it multiplies and matures.

Option 2: Kidney. This is the correct answer. The kidney is not a site of action for the malarial parasite. The parasite primarily affects the liver and red blood cells, not the kidneys.

Option 3: Red blood cell. After leaving the liver, the parasite infects red blood cells. This is where the parasite continues to replicate and causes symptoms such as fever, chills, and anemia.

Option 4: Brain. In severe cases of malaria, the parasite can infect the brain, leading to a condition called cerebral malaria. This can cause seizures, coma, and other neurological symptoms.

In summary, the malarial parasite Plasmodium primarily acts on the liver and red blood cells, not the kidneys.